1. Field of the Invention
This invention relates to stable thickened alkali metal hypochlorite bleaching compositions. More particularly, this invention is concerned with thickened compositions of alkali metal hypochlorites suitable as a clogged drain opening composition, for general cleaning use, or for laundry bleaching applications, which compositions in terms of viscosity and hypochlorite content are stable for many months, even years.
2. Discussion of the Prior Art
Aqueous solutions of alkali metal hypochlorite bleaching agents are widely used in the bleaching of textile materials, as well as in general purpose cleaning and bleaching of hard surfaces, including dishes, glasses, metal surfaces, pots, pans, and the like. In addition, in view of the capability of the bleaching agents to attack protein fibers such as hair and food particles, which are often the cause of clogged drains in bathroom and kitchen sinks, aqueous compositions containing alkali metal hypochlorite are used as liquid drain opening compositions, usually in combination with alkali metal hydroxide Such a composition is disclosed in U.S. Pat. No. 3,697,431 to Summerfelt.
Summerfelt teaches that wetting agents, or surface active agents, in amounts of from 0.25% to up to about 1% by weight, may be utilized to increase the rate at which the drain opener penetrates the fatty substance which clogs the drain. In amounts in excess of 1%, deterioration of the hypochlorite is accelerated. Anionic monophosphate esters of an ethoxylated alcohol or the salts of a perfluoracid are the only hypochlorite and hydroxide compatible wetting agents mentioned.
U.S. Pat. No. 4,116,850 to Ruck discloses drain opener compositions which are aqueous solutions of a soluble metallic hydroxide, a chlorine releasing agent, and a catalyst which is a metallic chloride of a Group VI metal. There is no suggestion of adding any thickening agents in either the Summerfelt, Ruck or Jones et al. patents.
U.S. Pat. No. 4,388,204 to Dimond et al. discloses a ternary thickener system containing an alkali metal salt of an N-alkyl, N-fatty acyl amino acid such as sodium lauroyl sarcosinate, an alkali metal salt of an alkyl sulfate such as sodium lauryl sulfate and an alkali metal sulfate salt of an aliphatic ethoxylated alcohol such as sodium lauryl ether sulfate. The data indicates that binary systems of these components failed to provide either sufficient viscosity increase or stability, or both.
In addition, the data indicates that the ternary thickener system components had to be present in narrowly defined ranges. Hence, each of the three components recited in the Dimond patent and their concentrations were critical to obtaining the desired composition properties.
Thickened alkali metal hypochlorite bleaching and cleaning compositions have also been suggested in view of the advantage of thickened compositions in bleaching and/or cleaning vertical surfaces. An extensive review of the prior art appears in U.S. Pat. No. 4,388,204 to Dimond et al.
The use of various detergents or surface-active agents for providing a thickening function in alkali metal hypochlorite bleach containing compositions has also been suggested. For example, U.S. Pat. No. 4,388,204 mentions numerous patents. In addition, U.S. Pat. No. 4,337,163 to Schilp discloses a thickened bleach composition containing as the thickening agent a mixture of a first detergent, e.g., an amine oxide, and a second detergent selected from the group of alkali-metal salts of saturated C.sub.8-18 fatty acids, alkali metal acylsarcosinates, alkali metal alkyltaurides, sugar esters, and alkali metal C.sub.10-18 alkyl ether sulfates with 1 to 10 moles of ethylene oxide and/or propylene oxide.
U.S. Pat. No. 4,375,421 to Rubin, et al., discloses viscous compositions containing alkylamido betaines and certain water-soluble inorganic or organic salts. The inorganic salts suitable are the sulfates of groups IA, IIA, IIB, and IIIA metals, sulfates of non-metallic ions, and alkali metal carbonates. Organic salts include citrates, tartrates, succinates, and carboxymethyloxy succinates of metals from the same groups as stated above. Also included may be a micelle-forming anionic surfactant, for example, sodium lauryl sulfate, sodium alphaolefin sulfonate, ammonium lauryl sulfate, ammonium laurylethoxy sulfate, and the like.
Also, British Patent No. 1,548,379 discloses a thickened bleach composition comprising an aqueous solution of an alkali metal hypochlorite containing as the thickening agent a mixture of a sucrose surfactant and another hypochlorite soluble surfactant, for example, a quaternary ammonium compound, amine oxide, a betaine, or an alkanolamide.
British Patent Application No. 2,003,552A discloses that an amine oxide derived from a synthetic fatty acid of certain structure provide greater viscosity increase when incorporated into the composition disclosed in U.K. Patent No. 1,329,086, wherein sodium laurate was used as the second surfactant in the thickener system.
However, there is still a need for less expensive, simpler thickened aqueous alkali metal hypochlorite compositions of improved stability both with regard to the hypochlorite concentration and the viscosity of the composition, as well as with respect to phase stability, i.e., there should not be any phase separation of the composition during storage, even over extended periods.
A major difficulty in finding suitable organic thickeners; lies in the interaction between thickeners and hypochlorites. Because of this interaction, both viscosity and hypochlorite concentration decrease as a function of time. The rate of hypochlorite degradation that occurs as a result of the interaction with the thickener is typically much faster than the reduction in hypochlorite concentration taking place in commercial hypochlorite solutions according to the equation: EQU NaOCl.dbd.NaCl+1/2O.sub.2
In many instances the compositions split into two phases. Moreover, many conventional thickeners are simply ineffective when used in aqueous hypochlorite compositions.
The problem of compatibility and stability between many classes of organic surface-active compounds and hypochlorite and the ineffectiveness of many conventional thickeners is well recognized and is discussed in several patents mentioned in U.S. Pat. No. 4,388,204. For example, Hynam, et al. U.S. Pat. No. 3,684,722 teaches the ineffectiveness of various polymeric thickeners, Veegum T, celluloses, silicones, water glass, bentonite, liquid paraffin, and sodium stearate (soap); Hartman U.S. Pat. Nos. 3,985,668 and 4,005,027 teaches that alkyl benzene sulfonates, olefin sulfonates, alkyl glyceryl ether sulfonates, alkyl ether sulfates and ethoxylated nonionic surfactants are to be avoided, while bleach stable surfactants that are especially resistant to hypochlorite oxidation fall into two main groups: water-soluble alkyl sulfates containing from about 8 to 18 carbon atoms in the alkyl group and water-soluble betaine surfactants.
Even among the classes of surfactants described in these patents as being compatible with and providing stable compositions with alkali metal hypochlorites, generally only a few of the many surfactants in each class are, in fact, stable enough for commercial applications.
Further extensive experiments and research to find hypochlorite compatible surfactants and especially surfactant mixtures revealed that only certain combinations of surfactant compounds and then only in certain critical proportions were capable of providing stable thickened hypochlorite bleaching compositions.
Accordingly, it is a object of the invention to provide stable thickened alkali metal hypochlorite compositions.
It is another object of the invention to provide a thickening additive composition which can be used to increase the viscosity of alkali metal hypochlorite compositions.
It is still another object of the invention to provide a thickened alkali metal hypochlorite composition for general purpose cleaning and laundry use, and for unclogging clogged drains, which is not expensive to produce and which remains stable for extended periods of time with regard to both product viscosity and hypochlorite ion concentration, as well as to phase stability.